Abstract

A method of resolving the complex conjugate ambiguity in Fourier-domain OCT is described. The complex differential spectral interferogram is obtained by simultaneous acquisition of the first and second harmonics of the ac component of the phase-modulated interferogram. The harmonics represent the imaginary and real parts of the interferogram, respectively. The complex conjugate rejection ratio is found to be at least 45dB and is limited by background noise.

Figures (2)

One-dimensional depth profiles with a mirror used as a sample obtained using the harmonic lock-in detection method: (a) no neutral density filter in the sample arm; (b) a 14dB neutral density filter in the sample arm; (c) sample arm blocked. The sidebands at −1240, −890, 650, and 1000μm are artifacts caused by a periodic miscalibration of the monochromator, possibly the result of small imperfections in the scanning mechanism of the device.